Forced EKS upgrade - when?

As you confirmed, your 1.21 cluster had End of standard support 15 Feb 2023, but extended support for a Kubernetes version will begin immediately after the end of standard support, and will end after the next 12 months. After the extended support, the cluster will be auto-upgraded to the next version.

Amazon EKS can't provide specific time frames. Automatic updates can happen at any time after the end of extended support date. You won't receive any notification before the update. We recommend that you proactively update your control plane without relying on the Amazon EKS automatic update process.

For more info, refer to https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html#extended-support-faqs

Hi,

As per https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html

Kubernetes version	Upstream release	Amazon EKS release	End of standard support	End of extended support
1.28	August 15, 2023	September 26, 2023	November 2024	November 2025
1.27	April 11, 2023	May 24, 2023	July 2024	July 2025
1.26	December 9, 2022	April 11, 2023	June 2024	June 2025
1.25	August 23, 2022	February 22, 2023	May 2024	May 2025
1.24	May 3, 2022	November 15, 2022	January 31, 2024	January 31, 2025
1.23	December 7, 2021	August 11, 2022	October 11, 2023	October 11, 2024

v1.23 is now at end of standard support. To remain supported you be switched to Extended Support, which has a cost (see page above).

See https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html

What if I don’t want to use extended support?
If you don’t want to be automatically enrolled in extended support, you can upgrade 
your cluster to a Kubernetes version that’s in standard Amazon EKS support. Clusters 
that aren’t upgraded to a Kubernetes version in standard support will automatically
 enter extended support.

So, if you don't want this extra cost, you have to upgrade rapidly

Best,

Didier